Contributors The authors from the School of Mathematics contributed to the work in this manuscript through the building of the simulation
model and analysing the data. The authors from the University Health Board provided the data needed and undertook the cost
analysis. All authors contributed to the writing of the manuscript.

Accepted 30 December 2011

Published Online First 14 February 2012

Abstract

Various approaches have been used to identify possible routes for improvement of patient flow within an emergency unit (EU).
One such approach is to use simulation to create a ‘real world’ model of an EU and carry out various tests to gauge ways of
improvement. This paper proposes a novel approach in which simulation is used to create a ‘perfect world model’. The EU at
a major UK hospital is modelled not as it is, but as it could be. The ‘efficiency gap’ between the ‘perfect world’ and the
‘real world’ demonstrates how operational research can be used effectively to identify the location of bottlenecks in the
current ‘whole hospital’ patient pathway and can be used in the planning and managing of hospital resources to ensure the
most effective use of those resources.